NVMIKE

First check out your ballistic tables to see what gives you the best overall performance, muzzle velocity doesnt mean much because you rarely get to stick your barrel against an animal and squeeze one off. As the small/fast bullets go downrange they loose speed/energy QUICKLY, so do those that are too large for the caliber. I think the difference in drop between the 150 & 180 is @ 3/4" at 300yds but almost 2" at 400. But energy @ 200yds is 2116/150gr 2325/180gr, the 180 will maintain energy better the farther you go. So.... compromise, I'd use the 165's. Bullet quality is more important, your better off hitting an elk on the money w/ a 130gr x-bullet than gut shooting him w/ a 180 gr soft point bullet. Use the very best bullets, X,failsafe, etc... If you like the 150gr and are used to them stick w/ them just use the premium bullets. Get one load that your gun likes and stick w/ it. As for 270's they are great for some things, but growing up out west I've come to know them as the elk woundingest S.O.B.'s on the market. But if your excellent w/ one dead is dead.